Plasma kinetics of an artificial emulsion resembling chylomicrons in patients with chronic lymphocytic leukemia

The Role of Cholesterol in Chronic Lymphocytic Leukemia Development and Pathogenesis

Cholesterol has many critical functions in cells. It is a key component of membranes and cell-signalling processes, and it functions as a chemical precursor in several biochemical pathways, such as Vitamin D and steroid synthesis. Cholesterol has also been implicated in the development and progression of various cancers, in which it is thought to promote cell proliferation, migration, and invasion. Chronic lymphocytic leukemia (CLL) is an example of a lipid-avid cancer that relies on lipid metabolism, rather than glycolysis, to fuel cell proliferation. However, data regarding the role of cholesterol in CLL are conflicting. Studies have shown that dyslipidaemia is more common among CLL patients than age-matched healthy controls, and that CLL patients who take cholesterol-lowering drugs, such as statins, appear to have improved survival rates. Therefore, defining the roles of cholesterol in CLL may highlight the importance of monitoring and managing hyperlipidaemia as part of the routine management of patients with CLL. In this review, we discuss the roles of cholesterol in the context of CLL by examining the literature concerning the trafficking, uptake, endogenous synthesis, and intracellular handling of this lipid. Data from clinical trials investigating various classes of cholesterol and lipid-lowering drugs in CLL are also discussed.

Cholesterol Levels in Patients with Chronic Lymphocytic Leukemia

Low cholesterol levels may be accompanied by solid tumors or hematological malignancies such as multiple myeloma. Decreased cholesterol levels have been reported in some experimental studies about chronic lymphocytic leukemia (CLL). It may be associated with tumoral cell metabolism. Herein, we examine blood lipid profiles of patients with newly diagnosed CLL (284 male, 276 female, mean age 64 ± 11 years) as defined by National Cancer Institute criteria. The control group consisted of 71 healthy subjects with mean age 55 ± 9 years (28 male, 43 females). 60% of patients with Binet A, while 25% were Binet C. Decreased levels of total cholesterol, high density lipoprotein (HDL) and low density lipoprotein (LDL) were observed in patients with CLL than control group (p < 0,001). There was no statistical significance between CLL and control group for triglycerides (TG) and very low density lipoprotein (VLDL), also between HDL-C, VLDL, TG and grades. Cholesterol may metabolized by abnormal lymphocytes in CLL patients.

Photothermal and photoacoustic Raman cytometry in vitro and in vivo

An integrated Raman-based cytometry was developed with photothermal (PT) and photoacoustic (PA) detection of Raman-induced thermal and acoustic signals in biological samples with Raman-active vibrational modes. The two-frequency, spatially and temporally overlapping pump-Stokes excitation in counterpropagating geometry was provided by a nanosecond tunable (420-2300 nm) optical parametric oscillator and a Raman shifter (639 nm) pumped by a double-pulsed Q-switched Nd:YAG laser using microscopic and fiberoptic delivery of laser radiation. The PA and PT Raman detection and imaging technique was tested in vitro with benzene, acetone, olive oil, carbon nanotubes, chylomicron phantom, and cancer cells, and in vivo in single adipocytes in mouse mesentery model. The integration of linear and nonlinear PA and PT Raman scanning and flow cytometry has the potential to enhance its chemical specificity and sensitivity including nanobubble-based amplification (up to 10- fold) for detection of absorbing and nonabsorbing targets that are important for both basic and clinically relevant studies of lymph and blood biochemistry, cancer, and fat distribution at the single-cell level.

Lipid changes occuring in the course of hematological cancers

The relationship between plasma lipid levels and mortality from cardiovascular diseases has been shown in many studies, but there has been far less investigation into their relationship to non-cardiovascular diseases. The aim of this study was to investigate the lipid profile of individuals with hematological malignancies and its relationship to disease activity. 238 patients were included in the study: 84 with acute leukemia, 62 with non-Hodgkin lymphoma, 35 with Hodgkin's lymphoma, 32 with multiple myeloma, and 25 with myeloproliferative syndrome. The HDL cholesterol level of the patients differed to that of the individuals in the control group in the active disease period for all the analyzed disorders, but only remained statistically significant in the acute leukemia and non-Hodgkin lymphoma groups during the remission period. Smaller differences were observed for the remaining lipid fractions, except for the triglyceride level, which increased in the active disease period in all the analyzed disorders except non-Hodgkin lymphoma. The most pronounced changes in the lipid fractions occurred in the HDL cholesterol level, and were the most remarkable for acute leukemia.

Cytotoxic effect of a lipophilic alkylating agent after incorporation into low density lipoprotein or emulsions: Studies in human leukemic cells

The use of low density lipoprotein (LDL) as drug carrier in acute myeloblastic leukemia chemotherapy is attractive due to high LDL uptake by leukemic cells. Lipid-based formulations, such as liposomes or microemulsions are promising alternatives. In the current study, we incorporated N-trifluoroacetyl-adriamycin-14-valerate (AD32), a lipophilic derivative of daunorubicin (DNR), and WB4291, a lipophilic alkylating agent, into LDL or lipid microemulsions and evaluated their cytotoxic activities towards leukemic cell lines using as references DNR and melphalan. The incorporation of AD32 into LDL or emulsion resulted in complexes with poor cytotoxicity. WB4291-LDL and WB4291-emulsion exerted, on the other hand, promising cytotoxic effects towards parental and resistant K562 and HL60 cell lines.

Cholesteryl esters in malignancy

Cholesteryl esters, formed by the esterification of cholesterol with long-chain fatty acids, on one hand, are the means by which cholesterol is transported through the blood by lipoproteins, on the other, the way cholesterol itself can be accumulated in the cells. Therefore, these important molecules play an active part in metabolic pathways that form the basis of cholesterol trafficking and homeostasis. The role of different regulatory mechanisms in cholesterol homeostasis in physiologic and neoplastic conditions with emphasis on intracellular content of cholesteryl esters is here reviewed. Numerous studies carried out on tumor cell lines, experimental tumors, and human tumors have shown an abnormal cholesterol metabolism that is reflected by an increase in intracellular cholesteryl esters due to an alteration in all the mechanisms that form the basis of regulation, in particular: cholesterol de novo biosynthesis; uptake of exogenous cholesterol LDL receptor mediated; cholesterol esterification mediated by the ACAT activity; cholesterol efflux HDL receptor mediated. The most recent analytic-spectroscopic applications that permit cholesteryl ester determination on tumor lipidic extracts and directly in vivo are also reported. This review gives an overview of cholesterol homeostasis in physiological and pathological conditions where cholesteryl esters are over-expressed.

Relationships in women between body mass index and the intravascular metabolism of chylomicron-like emulsions

OBJECTIVE

To investigate whether increasing body mass index (BMI) produces increasingly intense disturbances in the metabolism of chylomicrons, the lipoproteins that carry the dietary lipids absorbed by the intestine in the circulation.

SUBJECTS

Four groups of 10 normolipidemic nondiabetic women at the normal (BMI<25 kg/m(2)), preobese (BMI 25-30), obese (BMI 30-40) and morbid obese (BMI>40).

METHODS

Chylomicron metabolism was studied using the method of triglyceride-rich emulsions that mimic chylomicrons. The chylomicron-like emulsion doubly labeled with (3)H-triolein (TO) and (14)C-cholesteryl-oleate (CO) was intravenously injected to calculate the plasma fractional clearance rates (FCR, in min(-1)) by a compartmental analysis model. FCR-TO mirrors both the lipolysis from lipoprotein lipase that the emulsion suffers while still in the circulation, and the triglycerides portion that is not broken down and is removed from the plasma together with the remnant particles. Lipolysis index is calculated subtracting CO from TO areas under the curve.

RESULTS

FCR-TO did not differ among the four groups. The lipolysis index was positively correlated with BMI (r=0.310; P=0.05). On the other hand, FCR-CO progressively diminished from the normal to the morbid obese group (0.069+/-0.01; 0.064+/-0.01; 0.031+/-0.003; 0.029+/-0.005 min(-1), respectively, P=0.003) and there was a negative correlation between FCR-CO and BMI (r=-0.388; P=0.01).

CONCLUSION

In obesity, the capacity to break down chylomicron triglycerides by lipoprotein lipase in vivo increases, but the ability of the organism to remove the resulting chylomicron remnants particles progressively diminishes as the BMI rises. Remnant accumulation most likely predisposes to coronary artery disease development.

Metabolism of chylomicron-like emulsions in patients with Hodgkin's and with non-Hodgkin's lymphoma

BACKGROUND

Chylomicrons carry in the bloodstream dietary fats absorbed the intestine for storage in the body tissues such as adipose and muscle. The two-step chylomicron metabolism consists in lipolysis by lipoprotein lipase on vessel walls and hepatic uptake of triglyceride-depleted remnants. Chylomicron metabolism is understudied in cancer, despite its direct involvement in the patient nutritional status. We investigated this metabolism in Hodgkin and non-Hodgkin lymphoma patients, using the method of triglyceride-rich emulsions that mimic chylomicrons.

PATIENTS AND METHODS

The chylomicron-like emulsion, labeled with [9,10-3H]glycerol-trioleate and [1-14C] cholesteryl-oleate was intravenously injected into 11 Hodgkin's, 19 non-Hodgkin's patients and 12 healthy subjects. Triglyceride kinetics evaluate lipolysis whereas cholesteryl ester kinetics evaluate remnant removal.

RESULTS

Plasma total, LDL, HDL cholesterol, apo B, apo A1 and Lp(a) values were similar between the three groups, but VLDL cholesterol and triglycerides were higher in the lymphoma groups. The fractional catabolic rate (FCR, in min(-1)) of the emulsion triglycerides was roughly three-fold smaller in non-Hodgkin's (0.043+/-0.007, mean+/-S.E.M., P<0.001) and Hodgkin's (0.045+/-0.009, P<0.0001) lymphoma patients compared with the control values (0.151+/-0.032). FCR of the emulsion cholesteryl esters, was four-fold smaller in non-Hodgkin's (0.016+/-0.002, P<0.0001), and three-fold in Hodgkin's lymphoma patients (0.024+/-0.006, P<0.001) compared with the control group (0.069+/-0.013). The lipolysis index, calculated from the decay curves of both isotopes was also markedly smaller in both groups of lymphoma patients compared with the controls.

CONCLUSIONS

In both lymphoma groups, marked alterations in chylomicron lipolysis and remnant removal occurs.